Antiabrasion photographic coating



'.June 1o, 1930.

SIE. sH'EPPARD Er Al.r ANTIABRASIONv PHOTOGRPHIC COAT'ING' Filed Feb. 19. v1929 Sens/'fl ed conf/gg 2 INV E ATTORNEY Patented June 10, 1930 UNITED STATES PATENT olfr'lcEI SAMUEL E. SHEPPARD AND JAMES G. McNAL-LY, OF ROCHESTER, NEW YORK, ASSIGN'- ORS TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK ANTIABRASION PHOTOGRAPHIC COATIIIN'G' Application led February 19, 1929. Serial No. 341,195.

This invention relates to photographic films and plates and more particularly to anti-abrasion coatings therefor.

In connection with many types of photographic materials it is customary to provide an antiabrasion coating commonly known as an over-coating for' the photographic emulsion to prevent or reduce abrasion markings thereon. Gelatin has been widely used for this purpose especially on gelatino-silver halide emulsions, but the insolubility of the dried gelatin is uch in the aqueous developing solution that 1t resists the diffusion of the developer. This is especially true with X- ray emulsions where the over-coating must be 'of relatively considerable thickness in order to protect the delicateemulsion which is particularly susceptible to abrasion. Inthis instance the thickness of the over-coating is such that the rate of development is appreciably reduced.

In accordance with the present invention an over-coating for the emulsion is made from ous, lass-clear, film which. is strong and solution. Reference is made to the accompanying drawing, the single figure of which illustrates in perspective and on an enlarged scale a piece of film involving my invention, an edge of the film being shown in section.

We have found that poly vinyl alcohol or Oxy-ethylene as prepared by H.- Staudinger (Ber. 59, p. 3069, (1926) and W. O. Herrmann and W. I-Iaehnel (Ber. 60, p. 1658, (1927) may be used with ladvantage to form an anti-abrasion coating. As a specific example of this use, a solution of this ma terial in water at 10% 'concentration c'an be n coated in known-manner,'sixnilar to the coatmg of starch, sizes, and the like, which protects the emulsion from shearing, stresses,-

abrasions and the like. Unlike an over-coating of gelatin, anover-coating-of poly vinyl alcohol or oxy-ethylene when applied in the manner above described and subsequently dried, dissolves readily in water or the aqueous developing solution and thus does n ot offer resistance to the diffusion ofthe a synthetic product in theform of a continuv a transparent support, a layer of sensitized readiy soluble in anl aqueous developing veloper so'that the time of developing may be appreciably reduced.

In'addition to this property of solubility I an over-coating of the material of the present invention, is continuous," glass-clear, highly resistant to abrasion, and strong even when applied as a thin protective film to a photographic emulsion.

In order to illustrate one form in which the invention may be utilized reference is made to the accompanying drawing wherein 1 is a transparent support such as cellulosic material; 2 is a sensitized photographic emulto the back ofthe Celluloid support to prevent curling. A

What'we clalm 1s: l 1. An artlcle of manufacture comprising vlayer formed from a solution in water of poly vinyl alcohol at a concentration of the order of 10%- signedaatochester, New York, this 13th'v L E; SHEPPARD.

day'of February, 1929. l

- SAMUE .TABLES G. MCNALLY. 

